Crawler tractor



FIG. 1 is a perspective view of a crawler tractor showing a new design;

FIG. 2 is a right side view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a front side view thereof;

FIG. 5 is a rear side view thereof; and,

FIG. 6 is a top plan view thereof.

The broken line is environmental only and forms no part of the claimed design. 

The ornamental design for a crawler tractor, as shown and described. 